[en] Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. <BR /> Aims: In high-magnification events, the lens caustic may cross over the source disk, which allows determination of the angular size of the source and measurement of its limb darkening. <BR /> Methods: When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczyński point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients. <BR /> Results: In the case of the microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification at about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700[SUP]+100[/SUP][SUB]-200[/SUB] K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ± 100 K. <BR /> Conclusions: Because the limb-darkening measurements, at least in the CTIO/SMARTS2 V_s- and I_s-bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Fouqué, P.; Probing Lensing Anomalies Network, ; LATT, Université de Toulouse, CNRS, 14 avenue Edouard Belin, 31400 Toulouse, France
Heyrovský, D.; Institute of Theoretical Physics, Charles University, V Holešovičkách 2, 18000 Prague, Czech Republic
Dong, S.; Microlensing Follow Up Network, ; Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
Gould, A.; Microlensing Follow Up Network, ; Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
Udalski, A.; The Optical Gravitational Lensing Experiment, ; Warsaw University Observatory. Al. Ujazdowskie 4, 00-478 Warszawa, Poland
Albrow, M. D.; Probing Lensing Anomalies Network, ; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Batista, V.; Probing Lensing Anomalies Network, ; Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
Beaulieu, J*-P; Probing Lensing Anomalies Network, ; Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
Bennett, D. P.; Probing Lensing Anomalies Network, ; Microlensing Observations in Astrophysics, ; University of Texas, McDonald Observatory, 16120 St Hwy Spur 78, Fort Davis TX 79734, USA
Bond, I. A.; Microlensing Observations in Astrophysics, ; Institute of Information and Mathematical Sciences, Massey University, Private Bag 102-904, North Shore Mail Centre, Auckland, New Zealand
Bramich, D. M.; Probing Lensing Anomalies Network, ; Robotic Telescope Network, ; European Southern Observatory (ESO), Karl-Schwarzschild-Straße 2, 85748 Garching bei München, Germany
Calchi Novati, S.; Dipartimento di Fisica, Universita' di Salerno and INFN, sez. di Napoli, Italy
Cassan, A.; Probing Lensing Anomalies Network, ; Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
Coutures, C.; Probing Lensing Anomalies Network, ; Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
Dieters, S.; Probing Lensing Anomalies Network, ; Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
Dominik, M.; Probing Lensing Anomalies Network, ; Robotic Telescope Network, ; Microlensing Network for the Detection of Small Terrestrial Exoplanets, ; Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
Dominis Prester, D.; Probing Lensing Anomalies Network, ; Physics Department, Faculty of Arts and Sciences, University of Rijeka, Omladinska 14, 51000 Rijeka, Croatia
Greenhill, J.; Probing Lensing Anomalies Network, ; School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
Horne, K.; Probing Lensing Anomalies Network, ; Robotic Telescope Network, ; Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
Jørgensen, U. G.; Microlensing Network for the Detection of Small Terrestrial Exoplanets, ; Dark Cosmology Centre, Københavns Universitet, Juliane Maries Vej 30, 2100 København, Denmark
Kozłowski, S.; Microlensing Follow Up Network, ; Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
Lee, C*-H; University Observatory Munich, Scheinerstrasse 1, 81679 München, Germany ; The Wendelstein Calar Alto Pixellensing Project,
Marquette, J*-B; Probing Lensing Anomalies Network, ; Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, 98bis Bd Arago, 75014 Paris, France
Mathiasen, M.; Microlensing Network for the Detection of Small Terrestrial Exoplanets, ; Dark Cosmology Centre, Københavns Universitet, Juliane Maries Vej 30, 2100 København, Denmark
Menzies, J.; Probing Lensing Anomalies Network, ; South African Astronomical Observatory, PO Box 9 Observatory 7925, South Africa
Monard, L. A. G.; Microlensing Follow Up Network, ; Bronberg Observatory, Pretoria, South Africa
Nishiyama, S.; Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan
Papadakis, I.; Microlensing Follow Up Network, ; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Street, R.; Probing Lensing Anomalies Network, ; Robotic Telescope Network, ; Las Cumbres Observatory, 6740B Cortona Dr, suite 102, Goleta, CA 93117, USA ; Department of Physics, Broida Hall, University of California, Santa Barbara CA 93106-9530, USA
Sumi, T.; Microlensing Observations in Astrophysics, ; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Caldwell, J. A. R.; University of Texas, McDonald Observatory, 16120 St Hwy Spur 78, Fort Davis TX 79734, USA
Cole, A.; School of Mathematics and Physics, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
Cook, K. H.; Institute of Geophysics and Planetary Physics (IGPP), L-413, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551, USA
Donatowicz, J.; Technical University of Vienna, Dept. of Computing, Wiedner Hauptstrasse 10, Vienna, Austria
Kains, N.; Robotic Telescope Network, ; Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
Kane, S. R.; NASA Exoplanet Science Institute, Caltech, MS 100-22, 770 South Wilson Avenue, Pasadena, CA 91125, USA
Martin, Rosa ; Centre Hospitalier Universitaire de Liège - CHU > Service d'Informations médico économiques (SIME) - Service facturation
Pollard, K. R.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Sahu, K. C.; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Tsapras, Y.; Robotic Telescope Network, ; Las Cumbres Observatory, 6740B Cortona Dr, suite 102, Goleta, CA 93117, USA ; School of Mathematical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
Wambsganss, J.; Microlensing Network for the Detection of Small Terrestrial Exoplanets, ; Astronomisches Rechen-Institut (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
Depoy, D. L.; Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
Gaudi, B. S.; Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
Han, C.; Department of Physics, Institute for Basic Science Research, Chungbuk National University, Chongju 361-763, Korea
Lee, C*-U; Korea Astronomy and Space Science Institute, 61-1, Whaam-Dong, Youseong-Gu, Daejeon 305-348, Korea
Park, B*-G; Korea Astronomy and Space Science Institute, 61-1, Whaam-Dong, Youseong-Gu, Daejeon 305-348, Korea
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Fukui, A.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Furusawa, K.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Gilmore, A. C.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Hearnshaw, J. B.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Itow, Y.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Kamiya, K.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Kilmartin, P. M.; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Korpela, A. V.; Mount John Observatory, PO Box 56, Lake Tekapo 8770, New Zealand
Lin, W.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Ling, C. H.; Technical University of Vienna, Dept. of Computing, Wiedner Hauptstrasse 10, Vienna, Austria
Masuda, K.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Matsubara, Y.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Miyake, N.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Muraki, Y.; Department of Physics, Konan University, Nishiokamoto 8-9-1, Kobe 658-8501, Japan
Nagaya, M.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Ohnishi, K.; Nagano National College of Technology, Nagano 381-8550, Japan
Okumura, T.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Perrott, Y.; Department of Physics, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
Rattenbury, N. J.; Robotic Telescope Network, ; Department of Physics, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
Saito, To; Tokyo Metropolitan College of Industrial Technology, Tokyo 116-0003, Japan
Sako, T.; Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, 464-8601, Japan
Sato, S.; Department of Physics and Astrophysics, Faculty of Science, Nagoya University, Nagoya 464-8602, Japan
Skuljan, L.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Sullivan, D.; Mount John Observatory, PO Box 56, Lake Tekapo 8770, New Zealand
Sweatman, W.; University of Canterbury, Department of Physics & Astronomy, Private Bag 4800, Christchurch 8020, New Zealand
Tristram, P. J.; Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
Allan, A.; School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
Bode, M. F.; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
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Clay, N.; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
Fraser, S. N.; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
Hawkins, E.; Las Cumbres Observatory, 6740B Cortona Dr, suite 102, Goleta, CA 93117, USA
Kerins, E.; Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL, UK
Lister, T. A.; Las Cumbres Observatory, 6740B Cortona Dr, suite 102, Goleta, CA 93117, USA
Mottram, C. J.; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
Saunders, E. S.; Las Cumbres Observatory, 6740B Cortona Dr, suite 102, Goleta, CA 93117, USA ; School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
Snodgrass, C.; Microlensing Network for the Detection of Small Terrestrial Exoplanets, ; European Southern Observatory (ESO), Casilla 19001, Vitacura 19, Santiago, Chile
Steele, I. A.; Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
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Hundertmark, M.; Institut für Astrophysik, Georg-August Universität, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
Kjærgaard, P.; Dark Cosmology Centre, Københavns Universitet, Juliane Maries Vej 30, 2100 København, Denmark
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